The present invention relates to a braking control system on a vehicle. It finds particular application in conjunction with controlling activation of a stop lamp and will be described with particular reference thereto. It will be appreciated, however, that the invention is also amenable to other applications.
An operator (e.g., driver) of an articulated vehicle (e.g., truck) typically has two methods of demanding application of trailer service brakes. The first method involves applying a pedal of a foot brake valve, which demands application of both tractor and trailer service brakes. The second method involves operating a hand brake valve located in a cab of the tractor, which only demands application of the trailer service brakes. The first and second methods may be used independent of each other. In other words, the operator of the vehicle may use the first method and/or the second method to apply the trailer service brakes.
Conventionally, respective pneumatic pressures (e.g., pneumatic signals) at delivery ports of the primary foot brake valve and the secondary foot brake valve are fluidly communicated to a first supply port of a double-check valve, and the pneumatic pressure (e.g., pneumatic signal) at a delivery port of the hand brake valve is fluidly communicated with a second supply port of the double-check valve. The higher of the respective pneumatic pressures (e.g., pneumatic signals) at the first and second supply ports of the double-check valve are fluidly communicated to both an electro/pneumatic stop light switch, which controls activation of the vehicle stop lights, and a trailer supply line for controlling the trailer service brakes. The pneumatic stop light switch activates the vehicle stop lights whenever the pneumatic pressure (e.g., pneumatic signal) received from the double-check valve is at least a predetermined pressure (e.g., 4 psi) and deactivates the vehicle stop lights whenever the pneumatic pressure (e.g., pneumatic signal) received from the double-check valve is less than the predetermined pressure. Therefore, the vehicle stop lights are activated based on the highest of three (3) pneumatic signals.
Upcoming regulation mandates will require electronic sensing of foot brake valve driver demand on all trailer towing vehicles. Electronically sensing foot brake valve driver demand will reduce the utility of activating a stop light switch based on the highest of three (3) pneumatic signals. Instead, the vehicle stop lights will be activated based on only a single electronic signal that indicates if either or both of the primary and secondary foot brake valves are activated to produce the predetermined pressure. Therefore, electronically sensing foot brake valve driver demand will likely reduce, or even eliminate, the use of the above described electro/pneumatic stop light switch.
The present invention provides a new and improved apparatus and method for controlling the vehicle stop lights.